By dillon
Date 2006-03-20 23:46
just wondering if someone can tell me how to convert from the raw to geophysical data for the new level 3 aqua/seawifs merged data. I'm just looking for the equation. I've used (10^((band*0.015))-2.0)) to convert seawifs raw chlor a data to mg/m3 in the past, but obviously that won't work for this data. thanks,
Dillon
By mike
Date 2006-03-21 00:17
If you are ever unsure of a conversion, you can always look at the file's hdf header to find out.. In this case the equation is:
chl = 10^( (raw*5.8137757e-05)-2.0 )
One way to view the hdf header is to use "ncdump -h":
$SEADAS/hdf/HDF4/bin/ncdump -h A20050912005120.L3m_MO_XS_CHLO_9
:Parameter = "Chlorophyll a concentration" ;
:Measure = "Mean" ;
:Units = "mg m^-3" ;
:Scaling = "logarithmic" ;
:Scaling Equation = "Base**((Slope*l3m_data) + Intercept) = Parameter value" ;
:Base = 10.f ;
:Slope = 5.8137757e-05f ;
:Intercept = -2.f ;
:Scaled Data Minimum = 0.0099999998f ;
:Scaled Data Maximum = 64.565399f ;
:Data Minimum = 0.001987f ;
:Data Maximum = 99.714912f ;
Topic Products and Algorithms / Satellite Data Products & Algorithms / merged product raw to geophysical data (locked) (3460 hits)
